In the Middle Ages only wealthy town people could afford to eat and drink from beautiful, coloured glazed cups and plates. But the glazing was made of lead, which found its way into the body if someone ate acidic foods.

"Lead poisoning can be the consequence when ingesting lead, which is a heavy metal. In the Middle Ages you could almost not avoid ingesting lead, if you were wealthy or living in an urban environment," said Associate Professor Kaare Lund Rasmussen, Department of Physics and Chemistry, University of Southern Denmark (SDU).

Rasmussen and colleagues have published a series of chemical and anthropological analyses of 207 skeletons from six cemeteries in northern Germany and Denmark.

"There really is a big difference in how much lead, the individuals from the cemeteries had in their bodies. This depended on whether they lived in the country or in a town," said Rasmussen.

"We see almost no lead in the bones from rural individuals, while the levels of this toxic metal were high in urban individuals," said Rasmussen.

In the Middle Ages wealthy Danes and Germans mainly lived in towns, while the rural population was generally poorer and more isolated. The wealthy could afford to eat and drink of glazed pottery, and this was the main source of lead poisoning.

Glazed pottery was not the only source of lead in the towns. Lead was also present in coins, stained glass windows and lead tiles on the roofs of important buildings. Drinking water was often collected from the roof, and this may also have been an important source of lead.

The research team also tested the skeletons for their content of mercury. Mercury was used to prepare the colour cinnabar, for gilding and as medicine against leprosy and syphilis.